diff --git a/flake.nix b/flake.nix
index 57c8fa475..19d61e62a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -50,7 +50,7 @@
             };
         };
         shell = common: prev: {
-          packages = prev.packages ++ (with common.pkgs; [ lld_10 lldb ]);
+          packages = prev.packages ++ (with common.pkgs; [ lld_10 lldb cargo-tarpaulin ]);
           env = prev.env ++ [
             { name = "HELIX_RUNTIME"; eval = "$PWD/runtime"; }
             { name = "RUST_BACKTRACE"; value = "1"; }